Early Paleozoic monzodiorite–granodiorite association in the northeastern flank of the South Mongolia–Khingan orogenic belt (Nora–Sukhotinsky Terrane): Age and tectonic setting
- Authors: Smirnov Y.V.1, Sorokin A.A.1, Kotov A.B.2, Sal’nikova E.B.2,3, Yakovleva S.Z.2, Gorokhovsky B.M.2
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Affiliations:
- Institute of Geology and Nature Management, Far East Branch
- Institute of Precambrian Geology and Geochronology
- St. Petersburg State University
- Issue: Vol 10, No 2 (2016)
- Pages: 123-131
- Section: Article
- URL: https://journals.rcsi.science/1819-7140/article/view/211061
- DOI: https://doi.org/10.1134/S1819714016020068
- ID: 211061
Cite item
Abstract
The paper presents the results of U–Pb geochronological and geochemical studies of the rocks of the monzodiorite–granodiorite association in the northeastern flank of the South Mongolia–Khingan orogenic belt, which composes a tectonic block among the provisionally Lower Paleozoic volcanosedimentary complexes of the Nora–Sukhotinsky Terrane. It is shown that the studied rocks have similar petrographic features (with the presence of transitional varieties) and form common trends in the petrographic diagrams. This suggests that they are members of a single magmatic association. The geochemical features of the monzodiorites, quartz monzodiorites, and granodiorites, in particular their enrichment in large ion lithophile elements (LILE) and depletion in some HFSE, indicate their similarity with island-arc magmatic rocks. The presence of monzonites and quartz monzonites in the studied monzodiorite–granodiorite association along with high K, Rb, Th, and Pb concentrations gives reasons to believe that it formed in active continental margin or ensialic island-arc environments. The granodiorites of the monzodiorite–granodiorite associations of the Nora–Sukhotinsky Terrane are dated at 440 ± 10 Ma and may be considered as a fragment of the early Silurian active continental margin or ensialic mature island arc in the structure of the South Mongolia–Khingan orogenic belt.
About the authors
Yu. V. Smirnov
Institute of Geology and Nature Management, Far East Branch
Email: sorokin@ascnet.ru
Russian Federation, per. Relochnyi 1, Blagoveshchensk, 675000
A. A. Sorokin
Institute of Geology and Nature Management, Far East Branch
Author for correspondence.
Email: sorokin@ascnet.ru
Russian Federation, per. Relochnyi 1, Blagoveshchensk, 675000
A. B. Kotov
Institute of Precambrian Geology and Geochronology
Email: sorokin@ascnet.ru
Russian Federation, nab. Makarova 2, Saint Petersburg, 199034
E. B. Sal’nikova
Institute of Precambrian Geology and Geochronology; St. Petersburg State University
Email: sorokin@ascnet.ru
Russian Federation, nab. Makarova 2, Saint Petersburg, 199034; Universitetskaya nab. 7/9, St. Petersburg, 199034
S. Z. Yakovleva
Institute of Precambrian Geology and Geochronology
Email: sorokin@ascnet.ru
Russian Federation, nab. Makarova 2, Saint Petersburg, 199034
B. M. Gorokhovsky
Institute of Precambrian Geology and Geochronology
Email: sorokin@ascnet.ru
Russian Federation, nab. Makarova 2, Saint Petersburg, 199034